Tesi etd-03302024-123904
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Tipo di tesi
Dottorato
Autore
MEUCCI, ANNALISA
URN
etd-03302024-123904
Titolo
Contribution to the advancement of cultivating Iris pallida Lam
Settore scientifico disciplinare
AGR/04
Corso di studi
Istituto di Scienze della Vita - PHD IN AGROBIOSCIENZE
Commissione
relatore Prof.ssa MENSUALI, ANNA
Parole chiave
- orris; fragrance; valorization; irones
Data inizio appello
09/07/2024;
Disponibilità
parziale
Riassunto analitico
Iris pallida Lam. (orris) is one of the most typical rustic species of the Mediterranean landscape, able to survive in a wide variety of harsh environments but also on marginal areas and on soils not suitable for food crops. It represents an additional income for small and medium sized Tuscan rural realities and is mostly cultivated as principal crop or associated with olive and vine trees to produce fragrances, even if it also has a wide use in the pharmaceutical field. Orris fragrance is obtained through the distillation of its rhizome, where the iridals, triterpenoids characteristic of this plant, are accumulated during the three years of cultivation. Rhizomes are therefore stored in ventilated rooms for other three years to let iridals oxidize and form irones, responsible for the violet scent of the essence. The first aim of this research is to investigate one of the main critical aspects of orris production chain: the little knowledge that we have on the effects of plant-environment interaction on rhizomes quality and quantity. Plant-environment interaction needs to be in deep analyzed, to understand better the influence of genotype and environment on iridals accumulation and irones production. Another important goal is to characterize different I. pallida ecotypes and investigate their adaptability to cultivation areas different from the traditional ones. Five ecotypes of I. pallida traditionally cultivated for perfumes production were selected, two from Italy and three provided by LMR-IFF company located in France, and transplanted into five different areas, two in Italy (Pisa and San Polo in Chianti) and three in France (Trets, Savigny and Vievigne); for each year of cultivation, both biometric measurements during the flowering and harvesting phases and analyses of rhizomes iridals and irones content were performed, to analyse differences among ecotype phenotypes and their metabolic profiles. A characterization of the environments selected was also performed every year, collecting meteo data and performing soil physical and chemical analyses. From the results obtained it is possible to deduce both a qualitative difference between the rhizomes of the ecotypes when grown in the same area and a response of each ecotype to diverse cultivation environments. Knowing the response of the ecotypes to different pedo-climatic conditions and their iridals and irones production could allow to maximize rhizomes quality and production, with important outcomes on the industrial processes related to orris butter and absolute obtaining.
Other issues that discourage orris cultivation are the traditional propagation method used for its cultivation (4-5 new shoots per rhizome) and the high density of transplant required (130000 plants ha-1), that lead to the scarcity of raw material for farmers that want to start or spread its cultivation. The state of the art indicates I. pallida in vitro propagation via somatic embryogenesis as the most effective propagation method, using immature flower components as starting tissue; however, there are no studies aimed at comparing the responses of different ecotypes of I. pallida to this technique. The second aim of the project is therefore to set up a new micropropagation protocol, to quickly obtain plants from selected orris ecotypes and provide an effective tool for industries specialized in the propagation sector. The results highlighted the different responses of the ecotypes to the in vitro protocol and demonstrated the effectiveness of somatic embryogenesis in producing I. pallida plantlets; this alternative propagation method could allow to produce plantlets without sacrificing sealable rhizome.
Moreover, to facilitate the scale up of the activities carried out by micropropagation companies, the Slow Growth Storage (SGS) method was adapted for the first time to orris conservation. The results showed that it is possible to cold-preserve orris plantlets for up to 90 days without significant damages. This conservation technique can be useful for germplasm conservation and can also be integrated in the micropropagation cycle of orris, helping to solve issues related to the traditional propagation method.
Being orris a rustic plant and a species with a high economic value, its application to cover soils not suitable for crops traditionally cultivated for human and livestock nutrition could be considered. A preliminary test on I. pallida capacity to tolerate salinity during the acclimatization phase of micropropagated plants was conducted, treating them with exogenous melatonin both during the in vitro phase and during their adaptation to field conditions. The results show that orris plants are able to survive also at 400 mM of soil salt concentration and that the melatonin spray treatment was able to protect orris rhizomes from salt side effects. The overall results of this study hold promising implications for increasing orris cultivation in Italy and potentially incentivize the utilization of abandoned land.
Other issues that discourage orris cultivation are the traditional propagation method used for its cultivation (4-5 new shoots per rhizome) and the high density of transplant required (130000 plants ha-1), that lead to the scarcity of raw material for farmers that want to start or spread its cultivation. The state of the art indicates I. pallida in vitro propagation via somatic embryogenesis as the most effective propagation method, using immature flower components as starting tissue; however, there are no studies aimed at comparing the responses of different ecotypes of I. pallida to this technique. The second aim of the project is therefore to set up a new micropropagation protocol, to quickly obtain plants from selected orris ecotypes and provide an effective tool for industries specialized in the propagation sector. The results highlighted the different responses of the ecotypes to the in vitro protocol and demonstrated the effectiveness of somatic embryogenesis in producing I. pallida plantlets; this alternative propagation method could allow to produce plantlets without sacrificing sealable rhizome.
Moreover, to facilitate the scale up of the activities carried out by micropropagation companies, the Slow Growth Storage (SGS) method was adapted for the first time to orris conservation. The results showed that it is possible to cold-preserve orris plantlets for up to 90 days without significant damages. This conservation technique can be useful for germplasm conservation and can also be integrated in the micropropagation cycle of orris, helping to solve issues related to the traditional propagation method.
Being orris a rustic plant and a species with a high economic value, its application to cover soils not suitable for crops traditionally cultivated for human and livestock nutrition could be considered. A preliminary test on I. pallida capacity to tolerate salinity during the acclimatization phase of micropropagated plants was conducted, treating them with exogenous melatonin both during the in vitro phase and during their adaptation to field conditions. The results show that orris plants are able to survive also at 400 mM of soil salt concentration and that the melatonin spray treatment was able to protect orris rhizomes from salt side effects. The overall results of this study hold promising implications for increasing orris cultivation in Italy and potentially incentivize the utilization of abandoned land.
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